Multi-celled cushion and method of its manufacture

ABSTRACT

A method for inflating a cushioning devices comprised of at least first and second distinct chambers having an interconnecting passage which provides fluid communication between the chambers. The method comprises either: (1) limiting the volume of at least one of the chambers, filling the chambers with a fluid at a single inflation pressure from a single inflation point and sealing the interconnecting passage, or (2) filling the chambers with a fluid at a single inflation pressure from a single inflation point compressing at least one of the distinct chambers, and sealing the interconnecting passage. The method is particularly suited to manufacture of a footwear cushion comprised of a body of elastomeric material having a plurality of sealed non-communicating cells having a single inflation point. At least two cells sharing a single sealed inflation passage are at different pressures.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cushioning device, primarily for usein athletic equipment, comprised of a plurality of individual cells anda method of its manufacture. More particularly, this invention relatesto a unique cushion comprised of an elastomeric body having a pluralityof fluid filled individual cells, at least two cells being at differentpressures. The method of manufacture of the invention provides theability to form cushions having a plurality of cells at a plurality ofpressures from a single fluid insertion point.

The cushion of the invention is particularly well-suited to be used as aportion of a sole in footwear. The cushion is especially beneficial inathletic footwear because the plurality of individual cells at differentpressures facilitates the construction of a stable shoe capable ofreadily absorbing, distributing, and returning the frequent, repetitive,and intense forces experienced in sporting activities. While theinvention will be described with particular reference to footwear, theinventive cushion is also recognized as suitable for other sports, andcommercial and industrial related applications, including racquethandles, helmets, bicycle seats, gloves, automotive interiors, carpetpadding, packaging material, medical and prosthetic devices, mattresses,clothing, braces, etc.

2. Description of the Art

Fluid filled cushions have been in existence for a very long time. U.S.Pat. No. 302,190 (1884), for example, describes one early attempt tofashion pneumatic cushioned footwear. However, until invention of thecushions described in U.S. Pat. Nos. 4,183,156 and 4,219,945, acommercially successful embodiment of fluid containing cushions forfootwear was not readily available. These patents describe an inflatedinsert having multiple intercommunicating gas containing chambers whichprovide fluid support of the sole of a foot in a comfortable andefficient manner. In fact, these fluid containing cushioning devices aregenerally considered superior shock absorbing members which protect thebones, muscles, and ligaments of the foot and leg and the various bodyorgans during walking, jumping, and running.

In attempts to improve on the technology disclosed in these patents, ithas often been considered an advantage to construct the fluid containingfootwear cushion from a plurality of non-communicating chambers. Afrequently cited advantage of non-communicating chambers is thecontinued functionality of the unit upon puncture of an individualchamber. In this regard, Taiwanese Utility Model No. 33,544 describes astacked arrangement of air cushions having two inflation points tofacilitate separate inflation of peripheral air chambers and central airunits. In this manner, puncture of one cell does not completely destroythe cushion's functionality.

In addition, it has been recognized that cushions comprised ofnon-communicating chambers at different pressures provide significantbenefits to the wearer. In this regard, the geometry of the foot and theanatomic load support requirements for the foot are constantly changingin any activity that involves foot motion. Regardless of the activityand the change in geometry, there exists an optimum interaction betweenthe foot and footwear which requires both good cushioning and alsostabilization of the foot for effective and controlled movements,comfort, and to trigger the body's inherent automatic nerve/muscleproprioceptive reactions.

In general, footwear preferably functions to keep the foot properly andcomfortably positioned, stabilized, and minimizes a tendency toward amedial and/or lateral rolling motion. In this regard, it has beenrecognized as desirable to construct a higher pressured periphery to thecushion to provide lateral stability and a lower pressured centralportion, possibly of several inter-communicating cells, to providegreater deflection and shock absorbance.

For example, U.S. Pat. No. 5,353,459 describes a method of inflating abladder comprised of at least a first and second distinct chamber. Thechambers are linked in fluid communication by an interconnecting portwith a fluid filled inlet in communication with the first chamber. Themethod comprises introducing a first pressurized fluid into the inlet toinflate the first and second chambers to a first predetermined pressure.The interconnecting port is then sealed to isolate the first chamberfrom the second chamber. Thereafter, the pressure is adjusted, thesecond chamber is pressurized, and the fluid inlet sealed.

Although this design provides a method of constructing a fluid filledcushion having non-communicating chambers at distinct pressures, certainlimitations exist. Moreover, the process requires a plurality ofpressurization adjustments and sequential sealing of the interconnectingports to achieve a plurality of chambers at different pressures.

In contrast, the method of the present invention provides the ability toconstruct a cushion having a plurality of non-communicating cells at aplurality of different pressures in a single inflation step andoptionally a single sealing step. In addition, the effectiveness of themethod allows construction of a cushion having a significantly morecomplex geometric arrangement of pressurized cells than has previouslybeen accomplished. Accordingly, a cushion having significantly improvedenergy return, shock absorbance, stability, durability, and longevitycan be economically produced.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of this invention to provide a newand improved cushioning device and a method for its manufacture.

It is an advantage of the present invention to provide a cushion havinga greater resistance to bottoming out, even at low inflation pressures.

A further advantage of the invention is provided by the inventivecushion's exceptional cushioning and technical performance with anelastomeric envelope wall which is very thin.

An advantage of the present inventive method of manufacture is theability to economically produce an anatomic support which includesarea(s) of high deflection potential for greater shock absorbance andarea(s) which are more firm for greater stability, without therequirement of mechanical type stabilizing devices, common in thefootwear industry.

A further advantage of the present invention and method of itsmanufacture is provided by the inventive cushion's ability to incurcertain punctures or failures of cells without loss of overallcushioning characteristics.

An additional advantage of the inventive method is the ability toproduce a cushioning element having a contoured thickness and designedpattern of cell pressures throughout the cushion to match therequirements of a particular sport or an individual's orthotic needs.

The cushion of this invention comprises a body of elastomeric materialhaving at least two sealed individual fluid containing cushioningchambers filled from a single inflation point at a single pressure, atleast one of them being pressurized to greater than 0 psi and thechambers being at different pressures.

The invention also provides a method for forming the inventive footwearcushion comprised of forming at least two chambers having aninterconnecting passage in an elastomeric body and either: (1) inflatingthe chambers from a single inlet, while limiting the natural volume ofat least one chamber, and then sealing the inlet and interconnectingpassage, or (2) inflating the chambers from a single inlet, sealing theinlet, limiting the natural volume of at least one chamber and thensealing the interconnecting passage. As utilized herein the term"natural volume" is intended to mean the unrestricted volume of achamber at a given pressure when filled with a gas, and the unrestrictedvolume of a chamber containing a given quantity of fluid when filledwith a liquid.

The chambers may be of virtually any size, shape, or thickness,depending on the application, i.e. bubbles, tubes, rectangles, squares,serprentine, herring bone, circular, elliptical, honeycomb, free-form,composite etc. Furthermore, the chambers may have internal"shape-defining" members. These internal shape defining members may becompression supporting, or non-compression supporting components.Similarly, the chambers may have different wall thicknesses or shapessuch that the dynamic instantaneous fluid pressures contained thereincause greater elastic deformation and volume change of the chambers inpredetermined regions thereby adding additional control to thecushioning characteristics of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention consists in the novel parts, construction, arrangements,combinations, and improvements shown and described. The accompanyingdrawings, which are incorporated in and constitute a part of thisspecification, illustrate several embodiments of the invention and,together with the description, serve to explain the principles of theinvention.

Of the drawings:

FIG. 1 is a top plan view of a cushion constructed in accord with theteachings of this invention;

FIG. 1A is a cross-sectional view taken along lines 1--1 of FIG. 1;

FIG. 2 is a top plan view of an uninflated, unsealed preform elastomericcushion used in the formation of the cushion of FIG. 1;

FIG. 3 is a perspective view of a shoe incorporating the inventivecushion;

FIGS. 4A-4C are cross-sectional views taken along line 4--4 of FIG. 3demonstrating the compressive tendencies of the inventive cushion;

FIG. 5 is a top plan view of a die member used in the inventive method,dashed lines demonstrating the relative position of a preformed cushion;

FIGS. 6A-6C are cross sectional views of the die unit of FIG. 5 takenalong lines 6--6 demonstrating the function of the die unit;

FIGS. 7 is a die member having a recessed working face, compatible withthe die member of FIG. 5 to provide matching chamber halves,particularly appropriate when forming spherical chambers;

FIG. 8 is a cross-sectional view of a preferred female mold used informing the inventive cushion;

FIG. 9 is a top plan view of a bicycle seat incorporating the inventivecushion;

FIGS. 10A-10E are cross-sectional views of exemplary cushion designsprepared according to the inventive method;

FIG. 11 is a top plan view of a schematic footsole cushion of a type inaccord with the present invention;

FIG. 12 is a cross-sectional view taken along lines 12--12 of FIG. 11;

FIG. 13A-13C are diagrammatic views of a method of constructing avariable pressured cushion when starting with a preformed inflated andsealed cushion having intercommunicating chambers;

FIG. 14A-14C are diagrammatic views of an alternative method ofconstructing a variable pressured cushion when starting with anuninflated preform having only chamber outline formed;

FIG. 15A-15B are alternative embodiment cushions according to thepresent invention;

FIG. 16 is a cross-sectional view of a tennis racquet including theinventive cushion as a dampening insert in the handle;

FIG. 17 is a cross-sectional view of a football helmet including theinventive cushion as a protection lining;

FIG. 18 is a perspective view of a glove incorporating the inventivedesign;

FIG. 19 is a perspective view of an alternative heel ped of theinvention design;

FIG. 20 is a top plan view of a brace designed in accord with thepresent invention; and

FIG. 21 is a further alternative footwear cushion in accord with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the present preferredembodiments of the invention. Examples of which are illustrated in theaccompanying drawings.

While the invention and inventive process will be described inconnection with preferred embodiments and procedures, it will beunderstood that it is not intended to limit the invention to thoseembodiments or procedures. On the contrary, it is intended to cover allalternatives, modifications, and equivalents as may be included withinthe spirit and scope of the invention defined by the appended claims.

Referring now to FIGS. 1, 1A and 3, the cushion 1 is demonstrated. Asseen in FIG. 3, cushion 1 is particularly suited as a heel ped for anarticle of footwear. The cushion 1 is formed by sealing together twolayers of elastomeric material--top layer 3 and bottom layer 5--inselect areas to create the unique cellular structure (See FIG. 1A).Particularly, the cellular structure is formed with a weld patterncomprised of a plurality of generally longitudinal welds 7 and generallytransverse welds 9 to form a preformed cushion unit having a pluralityof intercommunicating cells 8.

The cushion's general outline is formed by sealing the perimeter 2 oftwo compatible vacuum formed halves, layers 3 and 5. Of course, thecompatible elastomeric halves can also be formed by slush or "lost-wax"casting, rotoforming, blow molding, electro-static powder or vapordeposition, injection molding or any other technique known to thoseskilled in the art.

As seen in FIG. 2, the preformed unit includes common passages 11 thatpermit an inflatant medium to flow from one cell to another. It shouldbe noted that passages 11 are often shared by several cells.Particularly, an inflated fluid passing through inflation tube 6 willpass into cell A and common, shared passage 11 facilitates simultaneousinflation of cells B, C, and D with the fluid.

To form the completed cushion having a pattern of inflated cells atvarious pressures, the preformed unit is filled with a fluid by a needleor nozzle inserted in inflation tube 6, selected cells are compressed toreduce their volume a predetermined amount, and passages are selectivelyclosed, in this instance with welds 13. Optionally, some of the cellscan be in communication with one another. Importantly, the pressures ofindividual cells are custom tailored by this method, more fullydescribed below, to provide an exceptionally stable heel cushion.

Particularly, in the cushion of FIG. 1, the non-communicating cellsaround the perimeter of the cushion--operating as discrete sealedcells--are inflated to a higher pressure than the cells more centrallylocated on the longitudinal axis. In this manner, the heel is stabilizedby very firm, high pressure cells around the perimeter, and cushioned bythe low pressure cells toward the center. This design cups, stabilizes,and cradles the heel, reducing undesirable medial and lateral rollingmotions and tendency toward over-pronation and/or excessive supination,or rolling-off of the foot-bed during rapid lateral stops and blockingaction--as in tennis.

The stabilizing and cupping action of the cushion is particularly wellillustrated in FIGS. 4A-4C, which show the heel 14 of a right foot in ashoe equipped with the inventive cushion 15. As is apparent, theoutermost cell 17 on the medial side is pressurized to a higher pressurethan the next cell inward 18. The center cell 19 is at a still lowerpressure. The pressure of cells progressing to the lateral side of theshoe then increases again (See cells 20 and 22). The low pressure of thecenter cells provides a very comfortable "riding on air" feel, andallows the calcaneus to sink lower into the center portion of thecushion than the outer portion (See FIGS. 4B and 4C). The cupping andcradling action of the device is clearly visible in these drawings.Particularly, cell 19 deflects to the largest extent, cells 18 and 20 tothe next largest extent, and cells 17 and 22 the least. Accordingly, aconcave, "U"-shaped, stabilizing surface is created under loadedconditions. It is also noted that outer cell 17 on a medial side of theshoe is pressurized to a higher level than outer cell 22 on a lateralside of the shoe. This design provides a beneficial "banked track"effect during the blocking type maneuvers encountered in many sports.

A particular advantage of the inventive cushion of FIG. 1 is theconstruction of a large quantity of individually pressurized cells whichprovide the ability for the cushion to function exceptionally well atlow pressures. Since the fluid is trapped within a plurality ofrelatively small volume cells, internal fluid pressure within the cellsbuilds up rapidly, compared to prior art inflated cushions with largercells having a corresponding slower pressure increase duringcompression. Accordingly, the present inventive cushion can operate withlower inflation pressures without bottoming out. These low pressures,combined with the preferred spherical, hemispherical, or semi-sphericalshape of the cells, permits the cushion to operate at stress levelswithin the envelope film which are much lower--perhaps less thanhalf--the stress levels of prior products. Accordingly, unusually thinlayers of barrier material, preferably about 0.008" to about 0.030", aresuitable for use in the inventive cushion.

As will be apparent upon review of the several cushion embodiments,provided in the Figures, the inventive cushion is unique in the footwearindustry, providing a precisely controllable, technically superior andhighly versatile means to replace conventional foam midsoles. Inaddition, the cushion provides the ability to construct footwear havinga 360° visible cushion which is particularly beneficial in marketing.Furthermore, the cushion provides even higher level of durability andreliability than that of even successful prior fluid filled products.

It is an important feature of this invention to be able to inflate andseal different pressures or quantities of fluid within different cellsor combinations of cells in an expeditious manner, preferably in asingle inflation step, so that the cushions can be manufactured rapidlyand at a low cost. The novel inflation technique of this inventionpermits construction of the inventive multi-chambered cushioning devicehaving a variety of different pressures, in a rapid, inexpensive, andreliable manner by filling a plurality of cells at a single pressurefrom a single point, rather than a multiplicity of points or pressures.

Thus, a cushioning device for footwear can be easily customized in themanufacturing process to provide a unique range of sport specific, oruser specific products. For example, a mid-sole cushioning device couldhave the individual chambers within the overall load supportive areaprogrammed in the manufacturing process to achieve an optimized dynamicbalance between the key factors such as (a) cushioning, (b) heelstability, (c) mid-foot stability, (d) forefoot stability, (e)pronators, (f) supinators, (g) special medical orthoticsupport/cushioning requirements, (h) desirable heel strike to forefoot"toe off" propulsion rolling action. Therefore, the mid-sole cushioningdevice could be uniquely customized to specifically fill the technicalperformance, comfort-cushioning, and energy return requirements for awide variety of activities such as running, jumping, tennis, soccer,triple jumping, volley ball, rugby, walking, standing, dancing, golf,aerobics, hiking, etc.

Although the inventive cushion and method of manufacture is asignificant improvement, the present invention can also beneficiallyincorporate many aspects of prior footwear and cushion constructiontechniques, including many of the materials utilized therein.Accordingly, U.S. Pat. Nos. 3,005,272; 3,685,176; 3,760,056; 4,183,156;4,217,705; 4,219,945; 4,271,706; 4,287,250; 4,297,797; 4,340,626;4,370,754; 4,471,538; 4,486,901; 4,506,460; 4,724,627; 4,779,359;4,817,304; 4,829,682; 4,864,737; 4,864,738; 4,906,502; 4,936,029;5,042,176; 5,083,361; 5,097,607; 5,155,927; 5,228,217; 5,235,715;5,245,766; 5,283,963 ; 5,315,769; and, 5,353,459, are hereinincorporated by reference.

Preferred fluids used to fill the inventive cushion are captive gasessuch as nitrogen and non-polar large molecules, alone or in combinationwith air. The device can be self-inflating via diffusion pumping ormechanically inflated. Large molecule gases which have been foundparticularly suitable include the following: hexafluoroethane; sulfurhexafluorides; perfluoropropanes; perfluorobutanes; perfluoropentanes;perfluorohexanes; perfluoroheptane; octafluorocylcobutane;perfluorocyclobutanes; hexafluoropropylene; tetrafluoromethane;monochloropentafluoroethane; 1,2-dichlorotetra-fluoroethane;1,1,2-trichloro-1,2,2-trifluoroethane; chlorotrifluoroethylene;bromotrifluoromethane; and, monochlorotrifluoromethane. Two preferredgasses within this group are hexafluoroethane and sulfurhexafluoride.

Also considered as suitable fluids with which to fill the elastomericbody are incompressible fluids such as water, semi-gel liquids, oils,grease, soft or liquid wax, glycerine, soft soap, silicones, rheopexicfluids, thixotropic fluids, and corn syrups which exemplify but do notlimit the types of acceptable incompressible liquids. In addition, theinventive cushion can include a combination of compressible gases andincompressible liquids.

When incompressible liquids are the only fluid used to fill a cell, thepredominate description of "pressure" utilized throughout thisapplication is more precisely equated to the maximum volume of a cellrelative to expansion (stretching) of the elastomeric material fromwhich it is formed. Moreover, a cell which is only partially filled, isconsidered a low pressure embodiment, whereas a cell which is filled tothe point where the elastomeric material of the envelope is elasticallyexpanded, is considered high pressured.

The flexible elastomeric body is preferably comprised of elastomericmaterials selected from: high percentage nitrile rubber, halogenatedbutyl rubber, polyurethane, polyester elastomer, fluoroelastomer,chlorinated polyethylene, polyvinyl chloride, chlorosulfonatedpolyethylene, polyethylene/ethylene vinyl acetate copolymer, neoprene,butadiene acrylonitrile rubber, butadiene styrene rubber, ethylenepropylene polymer, natural rubber, high strength silicone rubber, lowdensity polyethylene, adduct rubber, sulfide rubber, methyl rubber, andthermoplastic rubber. Polyurethane is a particularly preferred materialfor construction of the barrier. When a crystallographic gas barrier isdesired, the elastomeric material can be constructed to includecrystalline polyester, nylon, propylene, graphite, glass, Kevlar, vaporor sputtering deposited metals, dielectric metal oxides and mica. Thesematerials and others known to those skilled in the art are selected toreduce the captive gas, for example nitrogen, diffusion through theelastomeric walls of the cushion.

An exemplary method of constructing the inventive cushion is describedby referring to FIG. 5, FIGS. 6A-6C and FIG. 7. FIG. 5 is a plan view ofa die 21 (typically constructed of aluminum or brass) including RFwelding electrode insertion sites 23 and 25. In this example, smallcircular electrodes 23a and cruciform electrodes 25a are used toseal-off selected communicating passages (See 11 of FIG. 2) between thecells. The outline of the preformed cushion 1 (FIG. 2) is portrayed bydotted lines. Die 21 also includes dielectric inserts 26, preferablycomprised of micarta, fiberglass, Kel-F, Teflon, phenolics, etc.

In this embodiment, cushion 1 is first inflated to a pre-determinedpreform pressure through inflation tube 6 which is then sealed. Next,the cushion is nestled into the recesses 27 of base plate 29 to properlyalign the sealing electrode sites. The die of FIG. 5 is then placed overthe cushion and aligned by means of guide pins 31 on the base plate 29.

To assure alignment, recesses 27 in base plate 29 accept the widestportions of the uninflated preformed unit and allow sufficient room forthe cells to expand when individual cells change pressure andaccordingly volume.

An alternative manner in which to assure alignment is to punchregistration holes in the perimeter of the elastomeric body. Theseregistration holes can be aligned over pins in the base plate of theinflation die assembly. Such an approach is particularly expeditiouswhen the cushion is comprised of a first flat side and a second cellularside (See FIGS. 15) because a flat part is difficult to position.

Referring particularly to FIGS. 6A-6C, the adjustable pads or blocks 26preferably comprised of a dielectric material, are provided within theinner cavities of the die 21 to compress individual cells 8 by variouspre-determined amounts. While held in a compressed state, the weldingelectrodes 23a and 25a are inserted through die 21 (and optionally die29) to seal select communicating passages (11 of FIG. 2) in thepreformed cushion.

The welding electrodes can be any shape, for example circularrectangular or cruciform in cross-section, provided they can seal offthe selected passages. Furthermore, although the method disclosed inthis embodiment employs RF welding electrodes, those skilled in the artwill recognize the ability to use other impulse electric heat sealingmechanisms, electromagnetic, ultrasonic, laser, and/or chemical sealingprocedures, etc.

As is seen most clearly in FIGS. 6A-6C, the blocks 26 change the volumeand, therefore, also the starting preform pressure throughout theindividual cells. Moreover, inflatant fluid is forced to other cells,thus creating a new maximum pressure throughout all cells or chambers.Since the RF welding electrodes seal the cells in this state (FIG. 6B),the cushion, when removed from the compressive state, with cellsexpanded to their uncompressed free standing volume (i.e. naturalvolume), have pressures in the selected compressed cells reduced to thedesired pre-determined level and uncompressed cells at a higher pressurethan in the preform. In this way, any pattern of sealed pressures withinthe various cells can be achieved.

Moreover, it is determined beforehand what the maximum pressure in theinflated cushion should be, as well as what the various compressed(reduced) volumes of individual cells should be, so that, when the cellsare sealed and subsequently allowed to return to their full, freestanding volumes, the final pressures in each of the individualcompressed cells will drop to the desired value. Cells that were allowedto expand without any constraint, prior to sealing-off of the inflationpassage would stay at the maximum pressure level achieved, at the timethe communication passages were sealed off.

FIGS. 13A-13C and 14A-14C exemplify the distinction of inflating firstand then tailoring the cellular pressures versus tailoring the cellularvolumes and then inflating to the desired maximum incremental chamberpressure. Particularly, FIGS. 13A-13C depict two sheets of elastomericmaterial 31 and 33 formed into cushion 35 and pre-pressurized topre-determined 18 psi intermediate pressure level. The cushion remain inplace in to a die unit 34. While all of the chambers remain in fluidcommunication with one another, die 34 is lowered and pressurized, cell.Thus, the total volume of the entire interconnected group of cells isreduced, and the fluid pressure throughout the assembly isproportionally increased in accordance with Charles Gas law, P₁ V₁ /T₁=P₂ V₂ /T₂, to a new pre-determined level (FIG. 13B) While compressed,the appropriate passages are sealed with electrodes to form a finishedcushion having a plurality of chambers with controlled differentpressures (FIG. 13C) after removal from the die assembly.

FIGS. 14A-14C exemplify a procedure in which two sheets the elastomericmaterial 36 and 38 are formed into uninflated cushion 39. The cushion isthen placed into a die unit 41. The die inserts then restrict thenatural volume of the interconnected cells, the volume restrictedcushion is inflated, and the appropriate passages are sealed. Thefinished cushion is accordingly comprised of a plurality of cells,pressurized at pre-determined different pressures.

Alternatively, the cushion can be produced in a "single" step operationby completing all steps of construction in the die. Particularly, ratherthan form a "preform" cushion which is inflated and sealed in the die,the cushion can also be constructed in the die. Moreover, there is norequirement to construct a preform elastomeric body. Particularly, anelastomeric body can be formed into a 3-D cellular configuration in thedie (or re-entry to soften the film, and pressure and/or vacuum formingto expand the film into the die cavity) and inflated while reducing thevolume of selected cells, then sealing the appropriate passages toachieve cells of the desired thickness, size, geometry, and pressures.

In this case, the weld lines to form the cellular structure are notnecessarily formed prior to inflation. Particularly, a two positionheat-sealing die can be used. In the first position, the die forms cellswith compressive force, the cell volume is adjusted and the unitinflated or vice-versa. Thereafter, the weld lines, held temporarilyclosed by compressive force, and inflation passages are sealed withelectrodes and the formed multi-pressure chamber cushion is removed fromthe die.

A preferred female mold for forming the elastomeric body cells in adie--i.e. avoiding the step of constructing a preformed unit--isillustrated in FIG. 8. The elastomeric material can be vacuum formed orblow molded into the die structure.

Blow molding of the pre-formed, three dimensional multi-chambered devicecan be done in the manner familiar to those skilled in the art, i.e. aparison or bubble of semi-molten highly viscous elastomer is blown. Whenthe bubble is of the desired size and wall thickness, a dual femalechambered mold is clamped around the bubble, pushing selected opposingwalls of the bubble together, creating strong junctures where thesemi-molten walls are squeezed together. The gas pressure within theparison is concurrently adjusted upward to push the unsupportedsemimolten walls of the bubble to fill the cavities in the die.Thereafter, the part is allowed to cool, the inventive cellularpressurization procedure described herein is applied, and the cushion isthen rejected from the die.

In either the blow molding process described above or a vacuum formingprocedure well known to those skilled in the art, the female mold ispreferred because the tapered shape of the mold creates the thickestregion of the drawn film 41 between each cell, in the weld area 43.Since this is the welded area, the flex fatigue life of the part whensubjected to cyclical compressive loading is improved. Preferably, thetaper is at least 10% of the nominal wall thickness of the film. Thefilm is thickest and best able to resist buckling near the region of theweld. It is in this region where almost all fatigue cracking of the filmand subsequent fatigue failures occur in conventional air cushions. Inaddition, the taper in the side walls of the inflated cells controls thebending and buckling of the side walls in an advantageous manner so asto reduce the degree of localized folding action and the sharpness ofthe bends in the film.

It is the job of a good cushioning product to provide good energy return(resilience) simultaneously while providing superior cushioning inaddition to the other technical and performance characteristicspreviously stated. The present Invention provides superior cushioning.Because the fluid medium can be sealed within individual cells, noenergy is lost due to the inflatant moving around. In addition, all ofthe impact shock energy is absorbed and efficiently stored in a diabaticcompression of the trapped gas and the elastic deformation of theelastomeric envelope film.

It has been a fundamental unfulfilled goal in the design of varioustypes of cushioning devices and products, to customize theload/deflection characteristics of those products to match theincremental, site specific load/deflection function needed throughoutthe load bearing area of the device. Many good and functional techniqueshave been devised an are in common use. Various types of foam,elastomeric rubber, captive gas and captive liquid systems are availablein the market. However, they all function by averaging-out theincremental "site-specific" cushioning of technical requirements of theproduct. For example, in the mid-sole of certain athletic shoes, themanufacturer layers several different density, wedge-shaped foamelements to achieve softer cushioning in one area and a more firmsupport in another area. Some gas and fluid systems do this by havingtwo or more large bags filled with a fluid with one or two flowrestrictive passages or one way check valves provided between the bags.The present invention solves these problems in a very unique,expeditious, simple, cost effective and highly useful manner. Thus analmost limitless spectrum of news beneficial, and cost competitiveproducts are easily attainable.

FIGS. 10-12, 19 and 21 describe alternate footwear embodiments of theinventive cushion. Particularly, the cushions can be constructed withdifferent cell sizes and/or pressure levels. For example, higherpressures can be introduced into the perimeter cells and lower pressuresin center cells, to achieve the general shape of FIG. 10A. This providesa helpful cupping configuration. If it is desired that this cushion beflat on the bottom, it can be foam encapsulated to give the FIG. 10Bconfiguration.

The elastomeric encapsulating foam is usually a polyurethane foam, apolyvinyl acetate foam, or a "PHYLON" type material. In some cases,however, a slow-memory, high hysterisis foam can be used to slow downthe energy return from the energy cells and to provide a degree ofmolding/contouring of the foam to match the contour of the bottom of thefoot.

A similar shape can be achieved, as in FIG. 10C, by configuring theuninflated pre-formed bottom portion so that individual cells expand adifferent amounts when pressurized to provide a flat bottom. Moreover,cells at different pressures can be formed of different elastomericthicknesses to expand to same size and shape in spite of the fact thatvarious cells have significantly different internal pressures.

A foam encapsulated version of the FIG. 1 cushion is shown in FIG. 10D.In FIG. 10D, recesses are formed in the molded side walls of the midsoleto expose the individual cells of the cushion. In FIG. 10E, the outermost cell, actually protrude beyond the foamed side walls of themidsole. This visible cushion enhances market appeal of the finishedproduct.

FIGS. 11 and 12 show a full length version of an inflated cushion whichcan be constructed in accord with this invention. This version includesa plurality of varied pressure cells to provide a customized superiorcushion for footwear. A wide variety of customized cushioning devicescan be easily manufactured to precisely meet the static and dynamicrequirements of any sport, various types of foot-plants, etc. usingempirical information from force plates and representative mathematicalmodels, to determine the best pressure in each incremental cushioningelement to achieve the overall optimum cushioning performance andtechnical characteristics for that specific application, or for aspecific athlete.

In FIG. 11, the cushion is shown with all cells closed off from oneanother at various pressures. However, certain groups of cells may beleft in communication with one another for certain applications. Theappropriate distributions of high, low, and medium pressures can be usedin individual cells to create a pattern of support performance andcomfort to match the needs of various portions of the plantar area ofthe foot. Thus, for example, the calcaneus and longitudinal arches canbe given added support, and the metatarsals more comfortably dynamicallyand anatomically cushioned.

FIG. 15A shows a sectional view of a half sphere or tube cushion. Thecushion of FIG. 15A is formed by welding a flat sheet upper portion 51of elastomeric material to a preformed cellular bottom sheet 53. Uponinflation, both top and bottom portions expand, with the top sheetexpanding less than the bottom sheet.

If a completely flat surface is desired (as in FIG. 15B), it can beachieved by first laminating a flat sheet of elastomeric envelope film55 to another layer of material 57 having higher modulus of elasticity(for example "Texin" available from Mobay Chemical Co.). Subsequentlythis assembly is then heat-sealed to a preformed cellular bottom portion59.

As demonstrated by FIGS. 9, 16, 17, 18 and 20 the inventive cushion isalso well suited to use in a variety of shock absorbing environments.Particularly, the cushion can be utilized in a bicycle seat, in thehandle of a tennis racquet, as a lining of a helmet, and as a brace.

Thus, it is apparent that there has been provided, in accordance withthe invention, a cushion and method of its manufacture that fullsatisfies the objects, aims, and advantages set forth above. While theinvention has been described in conjunction with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations would be apparent to those skilled in the art in light of theforegoing description. Accordingly, it is intended to embrace all suchalternatives, modifications, and variations as fall within the spiritand broad scope of the appended claims.

Having described the foregoing invention, I claim:
 1. A process formanufacture of a cushioning device, said process comprising the stepsof:(a) placing an elastomeric member between first and secondcooperative die members; (b) forming at least two distinct cells havinga fluid communication passage between said at least two cells in saidelastomeric member; (c) temporarily limiting the volume of at least oneof said cells to a greater extent than said other cell; (d) filling saidcells with a single fluid pressure from a single injection point; and,(e) sealing said passage while performing step (c) and after completionof step (d).
 2. The process of claim 1 wherein said elastomeric memberis blow-molded into said cooperative dies.
 3. The process of claim 1wherein said elastomeric member is vacuum and/or pressure formed betweensaid first and second die members.
 4. The process of claim 1 whereinsaid elastomeric member comprises a preformed, at least partially sealedelastomeric body.
 5. The process of claim 1 wherein at least one of saiddie members has recesses to house said cells.
 6. The process of claim 1wherein at least one cell is filled with said fluid to achieve apressure from between greater than 0 psi and
 50. 7. The process of claim1 wherein step (c) is initiated before step (d) is performed.
 8. Aprocess for manufacture of a cushioning device, said process comprisingthe steps of:(a) placing an elastomeric member between first and secondcooperative die members; (b) forming at least two distinct cells havinga fluid communication passage between at least two cells in saidelastomeric member; (c) temporarily limiting the volume of at least oneof said cells to a greater extent than said other cell; (d) filling saidcells with a fluid; (e) sealing said passage while performing step (c),and; (f) ending said temporary volume limiting of step (c) causing saidcells to expand such that at least several cells are at differentpressures.
 9. The process of claim 1 wherein step (d) is performedbefore step (c) is initiated.
 10. A process of manufacturing amulti-cellular cushioning device comprising forming an elastomeric bodyhaving a plurality of cells in fluid communication via passages, fillingsaid cells with a fluid to a single pressure from a single inflationpoint, temporarily adjusting the volume of said cells to differentamounts, simultaneously sealing at least several passages to achieve amulti-celled cushion having a plurality of cells no longer in fluidcommunication at several different pressures.